Shock resistant multiple switch assembly



March 9 1969 c. E. MARTIN 3,432,624

SHOCK RESISTANT MULTIPLE SWITCH ASSEMBLY Filed Aug. 11. 1967 Sheet Z of 2 INVENTOR. CARL E. NA/zfm March 1969 c. E. MARTIN 3,4325624 SHOCK RESISTANT MULTIPLE SWITCH ASSEMBLY Fi led Aug. 11, 1967 Sheet 2 of 2 I I jgglal ouome INVEN'IYJR'v CARI E. Manf'uv United States Patent 8 Claims ABSTRACT OF THE DISCLOSURE The disclosure describes a multiple switch assembly 10 having a plurality of parallel plunger assemblies 14 for actuating respective switches 15. Radial arms extend from the plunger assemblies for movement therewith. An inertia device is mounted parallel with the plunger assemblies 14. The inertia device 25 has a plunger 27 with a radial arm 30. Two holding bars 42 and 60 are slidably mounted transverse to the plunger assemblies 14. The bars 42 and 60 have a plurality of hook slots 45 and 62 formed therein respectively for receiving the arms 20. The hook slots 45 have inwardly projecting shoulders that oppose the inwardly projecting shoulders 67 of the hook slots 62. The bars 42 and are resiliently biased to move the shoulders 50 and 67 to intersect the. path of the arms 20. Lock slots 54 and 72 are formed in the bars 42 and 60 respectively for receiving the arm 30 to prevent movement of the bars "42 and 60 when shock forces are exerted on the assembly 10 parallel to the axes of plunger assemblies 14. I

Background of the invention This invention relates to multiple. switch assemblies and more particularly to shock and acceleration resistant multiple switch assemblies.

, There has been a substantial and a prolonged need in the electrical industry for multiple switch assemblies that are unaifected by shock and acceleration forces exerted in any direction. This is particularly'true in the design of multipleswitch assemblies that are used in an environment where substantial shock and acceleration forces are encountered, such as aboard space craft or military vehicles. The safety and integrity of an entire mission may depend upon the requirement that none of the switches ac cidentally release or actuate. The problem is. particularly acute in developing a locking mechanism that will prevent switches from being accidentally actuated or released when external forces are encountered along an axis parallel to the switch actuators. This problem is often referred to as the Z axis shock loading problem. Very elaborate and extensive electrical and mechanical devices have been devised in an attempt to solve this problem. However, none has been totally satisfactory.

' United States Letters Patent No. 3,126,457, issued Mar. 24, 1964, describes a multiple switch assembly wherein the switches are interlocked by a transverse track assembly to permit only one switch to be actuated at a given time and to hold the actuated switch until released manually. United States Letters Patent No. 3,297,834, issued Jan. 10, 1967, discloses a later modification of this multiple switch assembly having an improved holding mechanism that is unaffected by external forces perpendicular to the axes of the switch actuators. In both of these switch assemblies, it is still possible to accidentally release a depressed switch by shock or acceleration forces directed along the Z axis, i.e., parallel to the switch actuators.

One of the principal objects of this invention is to provide a multiple switch assembly having a locking mechanism to prevent accidental release of a depressed switch due to environ-mental shock, vibration or acceleration.

3,432,624 Patented Mar. 11, .1969

A further object of this invention is to provide a locking mechanism that is relatively small and can be incorporated in conventional switch housing assemblies without undue difliculty.

An'addition'al object of this invention'is to provide a locking mechanism that is sensitive to forcescxerted along the Z axis to prevent switch actuators from moving to and from a depressed position.

A further object of this invention is to provide a device that is sensitive to shock forces along the Z axis that acts immediately to look a holding mechanism from releasing a depressed switch actuator prior to the movement of any of the other switch actuators in the multiple switch assembly.

Summary of the invention This invention concerns a multiple switch assembly having a locking mechanism for a multiple switch assembly having switch plunger assemblies with parallel switches movable to. and from depressed positions. The assembly includesa holding mechanism that is movably mounted to the assembly housing for releasing and holding the switch actuators in the depressed position. The assembly further includes an inertia device mounted to the assembly having a plunger assembly with a spring force to mass ratio less than the spring force to mass ratio of any of the switch plunger assemblies. The plunger of the inertia device is movable along an axis parallel to the movement of the actuators. When moved, the inertia device locks the switch actuator. Such movement will occur when the housing is subjected to an external force tending to move the ot-her actuators to the depressed position.

More particularly the assembly includes arms extending from the switch and inertia'plunger assemblies for move ment therewith. A track assembly is aflixed to the assembly having guide means for receiving and translationally guiding the arms. The holding mechanism includes a holding her that. is slidably mounted in the track. The holding bar hasa plurality of hook slots formed therein for receiving the'switch actuator arms. One side of each of the slots has an inwardly projecting shoulder formed thereon. The holding bar also has a lock slot formed therein for receiving the inertia plunger assembly arm to prevent movement of the holding bar when the inertia plunger assembly is depressed.

- Brief description of the drawings A preferred and other embodiments of this invention aregishown in the accompanying drawings, in which:

FIG. 1 is a perspective view of a multiple switch asinFIG. 1;

FIG. 4 is a cross-sectional view taken on line 44,

in FIG. 2;

FIG. 5 is an exploded view in perspective showing the various elements of a track assembly, holding mechanisms and an interlocking mechanism;

FIG. '6 is a series of schematic views proceeding from top to bottom showing the locking mechanism in operation.

Description of the preferred embodiments Referring now in detail to the drawings, there is shown in FIG. 1 a multiple switch assembly 10 havinga housing frame 11 with a side wall 12 and a face plate 13. The switch assembly 10 includes a plurality of push button type switch plunger assemblies 14 that are mounted in a row to operate respective switches 15. The switch plunger assemblies 14 extend through the face panel 13 and are movably mounted relative to switches 15 along axes parallel to the Z axis of the frame from an up or released position to a down or depressed position.

Each switch 15 is rigidly mounted to the housing frame 11 for receiving and resiliently supporting a respective plunger assembly 14. The switches that are shown are for illustration only and other switches for carrying out various switching functions when depressed can also be used. The switches serve to actuate circuit elements connected to the switches by means of terminals extending from the switch.

Each plunger assembly 14 includes a switch actuator 16 having a stem 17 that extends into the switch housing to actuate electrical contacts. A collar 18 is circumferentially mounted about each actuator 16. Each collar 18 has a radial engaging arm 20 formed thereon that projects from the actuator substantially along the Y axis of the assembly.

Each of the switches 15 has a switch housing 22 with a compression plunger assembly spring 23 mounted therein engaging the stem 17 for biasing the actuator to the up or released position. Each plunger assembly 14 has a predetermined spring force to movable mass ratio that defines the inertia characteristics of the particular plunger assembly.

An inertia device 25 is mounted to the frame 11 in line with the plunger assemblies 14 in much the same manner as the switches 15. The inertia device 25 has an envelope 7 that is similar to that of a combined single plunger assembly 14 and switch 15 except that it does not extend through the face plate 13. The inertia device has a plunger assembly with a housing 26 that is aflixed to the frame 11. A plunger 27 extends from the housing 26 and is movably mounted therein for movement along an axis parallel to the Z axis and to the axes of the actuators 16. A collar 28 is mounted circumferentially about the plunger 27. The collar 28 has a locking arm 30 formed therein that extends radially outward from the plunger 27- parallel to the Y axis. The collar 28 is located on the plunger by lock nuts 31 at a normal elevation below the collars 18. A compression spring 32 is mounted between the plunger 27 and the housing 26 to resiliently bias the plunger upward. The plunger 27 and the spring 32 have a predetermined spring force to mass ratio that is less than the spring force to mass ratios of any of the plunger assemblies 14. Thus for the same applied force, the switch plunger assemblies 14 will accelerate faster than the inertia plunger assembly.

A track assembly 35 that has a U-shaped crosssection is mounted facing the side wall 12 and extends parallel to the X axis of the switch assembly. Track assembly 35 is secured to the side wall 12 by a plurality of equally spaced bolts 36. The track assembly 35 consists of a horizontal wall 37, an upright wall 38 and a horizontal wall 39.

A plurality of guide means or, more specifically, elongated apertures 40 (FIG. 5) are formed in the Wall 38 substantially parallel to the Z axis. The apertures 40 are spaced longitudinally along the track at a distance that corresponds to the spacing between the arms 20 and 30. Each of the slots 40 has a width that is slightly greater than the width of an arm, 20 or 30. The slots 40 receive the arms 20 and 30 and guide the arms therein in a substantially translational movement parallel to the Z axis to prevent the arms from rotating.

The switch assembly 10 further includes a first holding means for holding and releasing the actuators 16 when they are in the depressed position. Particularly, the first holding means comprises a bar or slide 42 that is slidably mounted in the track 35 on the Wall 39 for movement parallel to the X axis. The bar 42 has a plurality of elongated apertures 43 formed therein for receiving the bolts 36 to enable the bar 42 to slide longitudinally back and forth between a first or left position and a sec- 0nd or right position.

A plurality of spaced transverse hook slots 45 are formed in the bar 42. The spacing between the slots 45 corresponds to the spacing between the switch plunger assembly arms 20. The slots 45 are aligned with the arms 20 to enable the arms 20 to move to the base of the slots when the bar 42 is moved to the right. Each hook slot 45 is substantially L-s'haped having a straight side wall 46, a bottom wall 47 and a contoured side wall 48. The contoured side wall 48 has an inwardly projecting shoulder 50 defining a side notch or indentation 51 for receiving and holding an arm 20 when the bar 42 is moved to the left. The shoulder 50' has an inclined up per surface 53 facing the open area defined by slot 45.

A lock slot 54 is formed in the bar 42 to receive the inertia device locking arm 30. To accommodate arm 30, the lock slot 54 is stepped with the width of the upper portion of the slot 54 being substantially equal to the length of the apertures 43. When the arm 30 is in its normal position, bar 42 is permitted to move between the first and second positions without engaging the arm 30. The lower portion of the slot 54 has straight side walls 56 and 57 and a bottom wall 58. The width of the lower segment of the slot 54 is only slightly greater than the width of the arm 30 so that the bar 42 will be unable to move along the X axis'when arm 30 is positioned therein.

The switch assembly 10 further includes a second holding means for holding and releasing the actuators 16 when they are in the depressed position. The second holding means comprises a bar 60 that is similar to but opposing the bar 42. The bar 60 is slidably mounted in the track 35 adjacent the bar 42. Like the bar 42 the bar 60 has a plurality of elongated apertures 61 formed therein for receiving the bolts 36 to enable the bar to slide back and forth between a first or right position and a second or left position.

The bar 60 has a plurality of transverse hook slots 62 formed therein along the bar in alignment to receive the arms 20 and directed oppositely to slots 54. Each of the hook slots 62 are L-shaped with a straight side wall 64, a bottom wall 65, and a contoured side wall 66. The

contoured wall 66 has an inwardly projecting shoulder 67 opposing the shoulders 50. The side wall 66 has a side indentation or notch 68 for receiving a depressed arm 20 when the bar 60 is moved to the right. The shoulder 67 has an inclined surface 71 facing the inclined surface 53 of the bar 42.

The bar 60- has a lock slot 72 formed therein similar to lock slot 54 formed in bar 42, with the component walls defining slot 72 turned opposite to the corresponding walls of slot 54.

The switch assembly 10 also includes a plurality of separable'members or slides 75 for interlocking the arms 20 so that no more than one actuator 16 may move to the depressed position at one time. The slides 75 are slidably mounted longitudinally in a row in the track assembly 35 adjacent bar 60. Each slide 75 has an elongated aperture 76 formed therein to receive one of the bolts 36 and to permit the slides to move back and forth. The length of each slide 75 is equal to the distance between the slots 45. Each end of the slides has a beveled upper surface 77 so that when two slides are abutting, a V is formed by the facing surfaces 77. The interlocking slides 75 are longitudinally positioned with respect to the length of apertures 76 in such a manner that when two adjacent slides 75 are separated a distance equal to the width of an arm 20, then the apertures of the other slides on both sides of the arm are abutting bolts 36 so that no more than one arm 20 is able to move downwardly to a depressed position at any one time.

A tension spring 80 with one end connected to the bar 42 and the other end connected to the bar 60 resiliently moves the bars to their respective positions so that the shoulders 50 and 67 intersect the path of the arms 20.

In operation, as may be particularly seen in the sequence views in FIG. 6, the switch actuators are normally in the up position. Initially, when one of the actuators is depressed by the operator, the arm designated as 20a for illustration purposes, is guided downwardly in the aperture 40 into engagement with the inclined surfaces 53a and 71a of the bars 42 and 60 respectively, to move the bar 42 to the right and bar 60 to the left against the tension of the spring 80. Further downward movement of arm 20a causes slides 75a and 75b to separate within the limits of apertures 76 and bolts 36 with slide 75b pushing slide 750 against 75d to prevent the other arms 20 from moving between the slides.

As the arm 20a moves below the shoulders 50a and 67a, the spring 80 moves the bars to their respective second positions with the shoulders 50a and 67a intersecting the path of the arms 20a to hold the arm 20a depressed as shown at the top of FIG. 6.

When it is desired to release the actuator arm 20a and to movethe arm 200 to the depressed position, the operator merely depresses the plunger assembly 14 associated with it to move the arm 20c downwardly as shown in the second view in FIG. 6 to engage the inclined surfaces 530 and 710 to move the bar 42 to the right and the bar 60 to the left. When the shoulders 50a and 67a are fully separated, the arm 20a is released to enable it to move to the up position and from between the slides 7 a and 75b as shown in the second view.

Further downward movement of the arm 20c causes the slides 75c and 75d to separate with slide 75c pushing slide 75b against 75a to prevent other arms 20- from moving to the depressed position. The third view shows the arm 20a returned to its original position and arm 20c held by the shoulders 50c and 670 in the depressed posi- 'tion.

Shock, acceleration or other external forces applied to the switch assembly frame along the Y axis do not affect the condition of the assembly since none of the parts are movable along the Y axis.

If external shock forces etc. are applied to the assembly frame along the X axis from left to right, bar 60 because of its mass will accelerate more slowly because of the resiliency of the spring 80 while the rest of the assembly accelerates. Thus, it is possible that a shock force directed from left to right along the *X axis, may cause the arm 20c to move from the notch 68c. However, the arm 200 is not released because it remains in notch 51c and is held in the down position by shoulder 50 of the bar 42.

If external shock forces etc. are applied to the assembly along the X axis from right to left, then bar 42 will temporarily tend to remain stationary against the resiliency of the spring 80 while the rest of the assembly accelerates. This could cause the arm 20 to move from the notch 51c. However, the arm 20c is held in the down position by shoulder 670 of bar 60.

During the deceleration phases of the shock forces along the X axis the action of bars 42 and 60 will be just the reverse tending to prevent the arm 200 from being released. Thus it may be said that the holding means (bars 42 and 60) are capable of holding the actuator in the depressed position when shock or acceleration forces are applied to the assembly along the X axis.

Turning now to the situation where external shock forces are applied to the frame along the Z axis, i.e. parallel to the movement of the actuators 16, the readers attention is directed to the fourth view in FIG. 6. If such forces are directed along the Z axis upwardly, the actuators 16 and plunger 27 initially tend to remain stationary against their respective springs 23 and 3-2 while the rest of the assembly accelerates. This causes the springs 23 and 32 to be compressed with the bars 42 and 60 moving upwardly toward the arms 20 and 30. Since the inertia device 25 including the plunger 27 and spring 32 has a spring force to movable mass ratio less than any of the spring force to movable mass ratios of the switchplunger assemblies 14, the lower portions of the lock slots 54 and 72 will receive arm 30 prior to the engagement of the inclined surfaces 53 and 71 with the arms 20. Thus the arm 30 will first enter slots 54 and 72 to prevent bars 42 and 60 from moving longitudinally to release the arm c.

Upon deceleration the actuators 16 will move back to their fully retracted positions faster than the plunger 27. Thus the arm 30 will not release the bars 42 and 60 until the arms 20 move from the inclined surfaces 53 and 71.

It should be appreciated that there are two important relationships between the switch plunger assemblies 14 and the inertia device that may be utilized to enable the lock slots to receive the arm prior to the engagement of the non-actuated arms 20 with the bars 42 and 60: (l) a spring force to movable mass ratio of the inertia device less than the spring force to movable mass ratios of the switch plunger assemblies and (2) the distance between the arm 30 and the slots 54 and '72 is less than the distance between the arms 20 and the slots and 65. Either or both relationships may be used in a single switch assembly 10.

In review then it may be said that the inertia device 25 prevents the holding means from accidentally releasing a depress-ed actuator or from allowing an actuator to accidentally move to the depressed position under Z axis shock locking conditions.

The combination of the inertia device 25 and the holding means (bars 42 and which may be referred to generically as a locking mechanism, prevents the accidental actuation or release of any of the multiple switch plunger assemblies when the assembly frame is subjected to external shock or acceleration forces in any direction.

It should be understood that the above described embodiment is simply an illustration of the principles of this invention. Numerous arrangements may be readily devised by those skilled in the art which will embody the principles of this invention and fall within the spirit and scope thereof.

What is claimed is:

1. A locking mechanism for a multi-switch assembly having a plurality of parallel switch plunger assemblies mounted to a housing frame, in which each switch plunger assembly has (1) a switch actuator that is movable to and from an actuating position and (2) a predetermined spring force to movable mass ratio, said locking mechanism comprising:

(a) a holding means movably mounted to said housing frame between a first location for receiving and releasing the switch actuators in the actuating positions and a second location for preventing the actuators from moving to and from the actuating positions; and

(b) an inertia device mounted to said housing frame,

the housing frame is subjected to an external force parallel to the switch actuators tending to move the switch actuators to the actuating positions.

2. The mechanism as defined in claim 1 wherein each of the actuators has an extending arm affixed thereto for movement therewith, and wherein the plunger has an extending arm affixed thereto for movement therewith, and wherein further the holding means includes a bar that is movable between the first and second locations, said bar having (a) hook slots formed therein aligned with the paths of the actuator arms for receiving and releasing the actuator arms when the bar is in the first location and for preventing the movement of the actuator arms to and from the actuating position when the bar is in the second location, and (b) a lock slot formed therein aligned with the path of the plunger arm for receiving the plunger arm when the bar is in the second position.

3. The mechanism as defined in claim 1 further comprising an interlocking means movably mounted to said housing frame for preventing more than one actuator from moving to the actuating position at one time.

4. A locking mechanism for a multi-switch assembly having a plurality of switch plunger assemblies mounted to a housing frame in which each of the plunger assemblies has an actuator that is movable along an axis that is parallel to a Z axis and perpendicular to an X and Y plane from a nonactuating position to an actuating position, said mechanism comprising:

(a) arms attached to the plunger assemblies for movement therewith;

(b) an inertia device mounted to said housing frame comprising:

(1) a plunger assembly movable along an axis parallel to a Z axis having a spring force to mass ratio less than the same ratio of any of the switch actuators; and

(2) a locking arm mounted to said plunger assembly for movement therewith;

(c) a track assembly afiixed to the housing frame, said track assembly having guide means for receiving and translationally guiding the actuator arms and the plunger arm; and v (d) a holding bar slidably mounted in said track assembly for movement parallel to the X axis, said bar comprising:

(1) a plurality of hook slots formed therein for receiving and releasing the respective actuator arms when the bar is in the first location and for preventing the movement of the actuator arms to and from the actuating position when the bar is in the second location; and

(2) a lock slot formed therein for receiving the locking arm to prevent the movement of the bar when the housing is subjected to an external force along the Z axis tending to move the actuators to the actuating position.

5. A mechanism as defined in claim 4 further comprising a resilient means for biasing the locking bar to the second location and wherein each of the hook slots has an inwardl projecting shoulder that extends into the path of the respective actuator arms when the bar is in the second location, each of said shoulder having an inclined upper surface formed thereon to enable the actuator arm to move against the inclined surface to move the bar against the resilient means to the first location.

6. The mechanism as defined in claim 5 further comprising an interlocking means having a series of longitudinally separable members that are slidably mounted in said track assembly for projecting into the paths of the actuator arms to prevent more than one actuator from moving to the actuating position at one time.

7. The mechanism as defined in' claim 4 wherein the inertia device is mounted to the housing so-that the distance between the locking arm and the lock slot is less than the distance from the actuating arms to the hook slots.

8. A three-axis shock resistant locking mechanism for a multi-switch assembly having switch plunger assemblies that are mounted to a housing frame in which each of the switch plunger assemblies has an actuator that is movable along an axis parallel to a Z axis and perpendicular to an X and Y plane from a nonactuating position to an actuating position, said mechanism comprising:

(a) engaging arms attached to the plunger assemblies for movement therewith;

(b) an inertia device mounted to said housing frame comprising:

(1) a plunger assembly movable along an axis parallel to the Z axis having a spring force to mass ratio less than the same ratio of any of the switch plunger assemblies; and

(2) a locking arm mounted to said inertia plunger assembly for movement therewith;

(c) a track assembly affixed to the housing frame, said track assembly having guide means for receiving and translationally guiding the engaging arms and the locking arm parallel to the Z axis;

(d) a first holding bar slidably mounted along the X axis in the track, said first bar comprising:

(1) a plurality of hook slots formed therein for receiving respective engaging arms, each of said hook slots having one side thereof formed in an inwardly projecting shoulder, and

(2) a lock slot formed therein for receiving the locking arm to prevent movement of the first bar;

(e) a second holding bar slidably mounted in the track parallel to the first bar, said'second bar comprising:

(1) a plurality of hook slots formed therein to receive respective engaging arms in which each of the hook slots has one side thereof formed with an inwardly projecting shoulder facing opposite the shoulders of the first bar; and

(2) a lock slot formed therein for receiving the locking arm to prevent the movement of the second bar; and

(f) resilient means operatively connected to the first and second bars for urging the opposing shoulders to intersect the translational paths of the engaging arms.

References Cited UNITED STATES PATENTS 1,704,582 3 1929 Stephenson. 1,773,392 8/ 1930 Eichenauer. 2,331,590 10/ 1943 Andres. 2,451,150 10/ 1948 Brian. 3,125,895 3/1964 Ross. 3,259,699 7/1966 De Rougemont et al. 3,320,372 5/1967 Lewandowski et al.

FOREIGN PATENTS 531,991 1/ 1941 Great Britain. 983,258 2/1965 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner.

US. Cl. X.R. 

62. THE BARS 42 AND 60 ARE RESILIENTLY BIASED TO MOVE THE SHOULDERS 50 AND 67 TO INTERSECT THE PATH OF THE ARMS
 20. LOCK SLOTS 54 AND 72 ARE FORMED IN THE BARS 42 AND 60 RESPECTIVELY FOR RECEIVING THE ARM 30 TO PREVENT MOVEMENT OF THE BARS 42 AND 60 WHEN SHOCK FORCES ARE EXERTED ON THE ASSEMBLY 10 PARALLEL TO THE AXES OF PLUNGER ASSEMBLIES
 14. 